Real-time Flu Forecasting Proves Successful in Large-scale Test

A flu forecasting system that uses some of the same techniques as modern weather forecasting was not only able to predict the timing of the 2012-2013 influenza season, but was able to do so nine weeks before the flu season peaked.

Columbia University researchers say there were able to correctly predict that flu activity in the southeastern United States would peak in December 2012, and that the rest of nation wouldn’t see its flu season crest until the first weeks of 2013.

The demonstration of Columbia University’s flu-predicting system follows the team’s study last year that predicted, in retrospect, the peak of the New York City flu season for each year between 2003 and 2008.

Predictions made in last year’s study were the initial test of the system and were limited to one city. The researchers said the new and expanded demonstration made its predictions in real-time for a number of cities throughout the country.

The timing of flu season can vary from year to year and from region to region. Influenza usually arrives any time between December and April, but when it does hit, a city can go from having no, or very few cases, to thousands within a short time period.

“Having greater advance warning of the timing and intensity of influenza outbreaks could prevent a portion of these influenza infections by providing actionable information to officials and the general public,” said study author Jeffrey Shaman, assistant professor at Columbia University’s Mailman School of Public Health.

This advance warning could provide people with information that might encourage them to get their flu vaccination, become more aware of their own personal health, and perhaps exercise extra caution when they’re around people who sneeze and cough.

To test their prediction system on a large scale, the researchers began to perform weekly estimates for 108 US cities in November 2012. The results of their weekly estimates were posted online and shared with the CDC.

They found that by the end of 2012, or four weeks into the flu season, their forecasting system had made accurate predictions in 63 percent of the cities they measured. That accuracy increased as the flu season moved forward. By the fourth week, the forecast system had accurately predicted the peak of the flu season in 70 percent of the country.

The flu forecasts were able to provide precise lead-times of up to nine weeks in advance of the peak, instead of the usual two-to-four weeks offered by other prediction methods that use historical data instead of real-time data.

A flu shot may sting a little bit but the US CDC recommends a yearly flu vaccine as the first and most important step in protecting ourselves against flu viruses. (Photo: US Navy)

In reviewing the results of their measurements, the researchers noticed regional differences regarding the accuracy of the system.

“We were able make better predictions in smaller cities. Population density may also be important,” said Shaman. “It suggests that in a city like New York, we may need to predict at a finer granularity, perhaps at the borough level. In a big sprawling city like Los Angeles, we may need to predict influenza at the level of individual neighborhoods.”

Shaman and his colleagues are gearing up for the 2013-2014 flu season and will be ready to put their forecasting system back into action as soon as it begins.

“Right now there are few cases of the flu, but as soon as the needle starts to move, we will start making predictions,” said Shaman.

Rick Pantaleo maintains the Science World blog and writes stories for VOA’s web and radio on a variety of science, technology and health topics. He also occasionally appears on various VOA programs to talk about the latest scientific news. Rick joined VOA in 1992 after a 20 year career in commercial broadcasting.